This question may be missing some important info to proceed, so I made it up along the way. For my made-up volume of gastric acid you need about 4.5 tablets. The dosage would be 5, probably.
Let's first obtain the HCl molarity in the gastric "juice" solution.
This is the balanced neutralization reaction.
Normally, there is some amount of solution to neutralize, here evidently none is given. I think this is almost needed in order to proceed (please correct me in the comments if not!), so I will make one up for example's sake. Let's say we have 1.50L of gastric "juice", a reasonable estimate.
Lastly, we'd then divide this mass of